<html>
 <body>
  <a href="http://sudopedia.enjoysudoku.com/Uniqueness_Test.html#Uniqueness_Test_3">Uniqueness Test 3</a> (Hidden {7})
   <p>
   The <b>{11} cells {3}</b> form a unique {0} with two common <b>candidates {1} and {2}</b>.
   There are two possibilities to place the two digits into the {11} cells which leads to an invalid puzzle with two solutions.
   This <a href="http://sudopedia.enjoysudoku.com/Deadly_Pattern.html">deadly pattern</a> must be avoided because a valid puzzle can have just one solution.
   To avoid the deadly pattern extra candidates in one or several of the {11} cells exist to eliminate other candidates in the puzzle. 
   </p>
   <p>
    To avoid the deadly pattern either <b>cell {4}</b> or <b>cell {5}</b> must contain one of the extra <b>candidates {6}</b>.
    If these two cells are treated as one virtual cell they form a <b>Hidden {7}</b> with <b>cells {8}</b> for the <b>digits {9}</b>.
    All other candidates can therefore be removed from the <b>cells {8}</b>.
  </p>
 </body>
</html>